AVG Antivirus vs. ClamWin

I have been using ClamWin now for a year or so. I liked the fact that it has a smaller footprint.

I was getting ready to try AVG Free again, when I noticed in the license that it was only free for personal use, and specifically excluded non-profit businesses from the license.

I get excluding business, but why Non-Profits? Just feeling uncharitable?
ClamWin is a Sourceforge open source project.

Anyway, no infections using ClamWin, so I continue on.

In addition, I use:
Windows Firewall (installed by default on XP and up)
Windows Defender
Firefox and Chrome


(Kim Kommando has her own set of recommendations for free security software)

Links:
ClamWin
AVG Free

[UPDATE: 2011-12]
On all but the lowest powered machines, I now install Microsoft's own Security Essentials .  I find that it generally does not impede performance, as I find with many other av software, and so far has been smooth.